Relationships between mineral concentrations and physicochemical characteristics in the Longissimus thoracis muscle of Japanese Black cattle

The relationship between mineral concentrations, and the relationship of mineral concentrations with physicochemical characteristics in muscles were investigated using the Longissimus thoracis (LT) muscle of 44 Japanese Black steers. We determined moisture content, fat content, meat color, fatty acid composition and mineral concentrations in the LT muscle. Magnesium (Mg), potassium (K) and zinc (Zn) concentrations had negative correlations with fat content, but sodium (Na), manganese (Mn), copper (Cu) and molybdenum (Mo) concentrations were not correlated with fat content. The concentrations of Mg, Mn, Fe, Cu and Zn largely and positively contributed to the first principal component of mineral concentrations. Because the red muscle was rich in these minerals compared to the white muscle, the variation of these minerals probably results from the abundance of red fibers in the LT muscle. The concentration of K was positively correlated with moisture content but Na concentration was not related to moisture content, suggesting that the intracellular fluid volume can largely affect moisture content. The results of the present experiment suggest that mineral concentrations reflect some traits such as not only fat content but also the composition of myofiber type and the intracellular fluid volume in the LT muscle of Japanese Black cattle.     

Q969R polymorphism in NLRP3 is associated with immune responses to vaccination against bacterial infections in pigs

Nucleotide‐binding domain, leucine‐rich‐containing family, pyrin‐domain containing‐3 (NLRP3) is an important pattern recognition receptor involved in various inflammatory responses and adjuvant effects upon vaccination. We previously identified the Q969R (A2906G) gain‐of‐function polymorphism in porcine NLRP3, which increased production of interleukin‐1β in in vitro gene transfection experiments. Here, we explored the associations between the A2906G polymorphism and antibody responses after vaccination against bacteria in Large White pigs maintained under specific pathogen‐free conditions. The NLRP3‐2906^A/G pigs had a greater antibody response to vaccine antigens than NLRP3‐2906^A/A pigs. We observed a significant association of the antibody response against Haemophilus parasuis serotype 2 and 5 with NLRP3 genotypes. As the A2906G polymorphism in NLRP3 is widely distributed in commercial pig breeds, Landrace, Large White and Berkshire pigs, there is potential for improvement in vaccine efficiency and disease resistance using this polymorphism in various pig populations.     

Diversity and population density of methanogens in the large intestine of pigs fed diets of different energy levels

Marker gene analysis was performed to assess the effect of energy level on the diversity and population density of methanogens in pig fecal material. Crossbred pigs were fed high or low energy level diets, a high‐energy (HE) diet that satisfied daily gain at 1.2 kg, and a low‐energy (LE) diet with amount of 0.6 times of the HE diet. Growth performance and short‐chain fatty acid in feces were examined. Diversity of methanogen was analyzed by the α‐subunit of methyl coenzyme‐M reductase gene (mcrA) clone library from fecal DNA. The DNA copy numbers of mcrA were quantified by real‐time PCR. There was no difference in the concentration and composition of short‐chain fatty acid between treatments. Differences in the mcrA clone library were observed between HE and LE treatments (p < 0.05). Ninety‐five percent of cloned sequence affiliated genus Methanobrevibacter in the feces of the pig regardless of treatments. During the experimental period, no significant difference in the proportion of copy numbers of mcrA against that of 16S rRNA gene of total bacteria was observed between treatments. In conclusion, feeding energy level affected composition of methanogens in the large intestine of the pig, while population density of methanogen was not affected.     

Shiga toxin 2eB‐transgenic lettuce vaccine is effective in protecting weaned piglets from edema disease caused by Shiga toxin‐producing Escherichia coli infection

Porcine edema disease (ED) is a toxemia that is caused by enteric infection with Shiga toxin 2e (Stx2e)‐producing Escherichia coli (STEC) and is associated with high mortality. Since ED occurs most frequently during the weaning period, preweaning vaccination of newborn piglets is required. We developed stx2eB‐transgenic lettuce as an oral vaccine candidate against ED and examined its protective efficacy using a piglet STEC infection model. Two serially developed Stx2eB‐lettuce strains, 2BN containing ingredient Stx2eB constituting a concentration level of 0.53 mg Stx2eB/g of powdered lettuce dry weight (DW) and 2BH containing ingredient Stx2eB constituting a concentration level of 2.3 mg of Stx2eB/g of powdered lettuce DW, were evaluated in three sequential experiments. Taken the results together, oral administration of Stx2eB‐lettuce vaccine was suggested to relieve the pathogenic symptoms of ED in piglets challenged with virulent STEC strain. Our data suggested that Stx2eB‐lettuce is a promising first oral vaccine candidate against ED.     

Influence of replacing brewers' grains with green tea grounds on feed intake, digestibility and ruminal fermentation characteristics of wethers

An experiment was conducted to examine feed intake, apparent digestibility, nitrogen balance, ruminal fermentation and blood components of wethers fed diets containing increasing levels of wet green tea grounds (WGTG). The experimental design was a 4 × 4 Latin square with four wethers in four 15‐day periods. Wethers were allowed access to diets ad libitum, and allotted to one of four treatments in which WGTG replaced 0% (no WGTG added, CTG), 5% (low level, LBG), 10% (medium level, MTG), and 15% (high level, HTG) of total mixed ration (TMR) dry matter (DM) as wet brewers grains (WBG). All TMR silages were ensiled for 120 days and, irrespective of the WGTG addition, they were well preserved with a high lactic acid content, low pH and ammonia‐N contents. There were no differences among treatments in feed intake, with the exception of ether extract intake (P = 0.032). Digestibilities for LTG and MTG treatments were not different from CTG. However, the organic matter, crude protein, acid detergent fiber and energy digestibilities for HTG treatment were lower than the CTG (P < 0.05). As the level of WGTG increased, nitrogen intake did not differ, but fecal nitrogen increased (P = 0.002), while urinary nitrogen decreased (P < 0.001). No differences among treatments were found in pH level and volatile fatty acids concentrations. However, the ruminal ammonia‐N of the HTG silage was lower than for the CTG silage at all times (P < 0.05). Increasing concentrations of WGTG in the TMR silage decreased (P = 0.019) plasma urea nitrogen content. Therefore, the possible mixing proportion of WGTG for TMR silages can be 10% of the diet DM.     

Community structure of microeukaryotes in a rice rhizosphere revealed by DNA-based PCR-DGGE

Rice roots provide a specific habitat for microorganisms in the rhizosphere of a submerged field through supply of oxygen and organic matter. Many studies have focused on the microbial community in the rice rhizosphere, but less is still known about the microeukaryotic community structure of rice rhizosphere. This study explored the microeukaryotic community structure of a rice rhizosphere through denaturing gradient gel electrophoresis (DGGE) targeting 18S rRNA gene. The rice roots and the rhizosphere soil samples, which were collected from a field under rice-wheat rotation system, were separately analyzed. To characterize the rice rhizosphere-specific community, the bulk soil of rice field and the wheat rhizosphere samples were also examined. DGGE fingerprints showed that the microeukaryotic community of rice roots were distinct from the community of the bulk soil and showed a temporal shift with the growth stage. The rhizosphere soil community was distinct from the root and bulk soil communities, but this could be explained by that the root and bulk soil communities were shared in the rhizosphere. The rice rhizosphere community was also distinct from those in the wheat rhizosphere. Microeukaryotes that characterized the rice rhizosphere (roots and the rhizosphere soil) community could be affiliated to Polymyxa, flagellates, and oomycetes, which suggested that microeukaryotes with various ecological roles, e.g., parasites, bacterial grazers, and decomposers, inhabit the rice rhizosphere. The results showed that the rice root and its growth stages are key factors shaping the microeukaryotic community structure in the rhizosphere.     

Degradation of an acylated starch-plastic mulch film in soil and impact on soil microflora

Degradation of an acylated starch-plastic mulch film was evaluated in two soil types, a gray lowland soil (A) and a volcanic andosol (V). Weight loss, tensile strength (TS) loss and loss of percentage elongation (%E) were measured under laboratory conditions (black and white mulch films), and in the field (black films). Changes in the counts of total bacteria, total fungi, gram-negative bacteria, total Fusarium, ATP (adenosine triphosphate) content, % nitrification, pH (H₂O), and total C and total N contents were determined at 4,8, 12, and 20 months in the field test soils where the mulch was repeatedly applied, and compared with controls. Film weight loss was greater in soil V than in soil A in both the laboratory and the field, and the losses were greater in the laboratory than in the field in both soils A and V. Significant TS losses and considerable %E losses were observed. Values were similar in the laboratory and in the field. No significant changes in the counts of bacteria, fungi, gram-negative bacteria, and Fusarium were observed. The ATP content of the test soils increased slightly compared with the initial values. The ATP content in the control soils initially fell, and then increased in response to weeding. Nitrification remained almost unchanged in the test soils, but fell in the control soils until the last sampling. However, the mulch film underwent a definite process of degradation in the soils, with great loss of physical properties and lesser weight loss. This degradation had no adverse impact on the soil microflora.